1. Field of the Invention
The present invention relates to an apparatus and method for providing negative pressure at a wound site. In particular, but not exclusively, the present invention relates to an apparatus including a source of negative pressure which acts as a negative pressure reservoir to continually or repeatedly “top up” an applied negative pressure so that negative pressure applied at a wound site can be maintained within desired limits for a relatively long period of time.
2. Description of the Related Art
Devices for the generation of negative pressure at the surface of skin have been used for many hundreds of years to treat animal and human bodies. For example the cupping technique (which relates to the positioning of a mouth of a rigid vessel containing hot air) is a well known technique. Spring powered syringes and suction cups are other mechanical techniques which have been used in the past for generating a vacuum on tissue. In common with cupping such techniques have, in the past, suffered from a very limited longevity of the therapy which can be applied. That is to say the duration of the negative pressure which can be maintained over a site of application has been limited.
To enable a more prolonged application of controlled negative pressure, powered systems, which include a vacuum generation source such as a pump of some type have been developed and many examples of such systems are used today for the management of wounds. However, many of these systems are not convenient for discreet use by a patient as they are large, can be heavy and are often noisy. Furthermore the production costs associated with such systems are substantial due largely to the cost of materials and complexity of assembly.
Attempts have been made to produce a mechanical device able to apply negative pressure to a wound site. It will be appreciated that such a mechanical device, due to its simplicity of design, would be expected to reduce material costs and assembly costs. For example, US 2008/200905 discloses a hand-pump system for the application of negative pressure at a tissue site. However, the system described does not enable prolonged convenient application of negative pressure at the wound site and in fact requires re-evacuation relatively often. This is a serious deficiency particularly as many such systems should ideally be useable overnight.